Web portals are massive systems where users come to consume content. Traditionally, web portals treat every visitor in the same manner in which all users are shown the same content. However, every user brings a unique set of preferences to the portal, and is interested in content that might not necessarily reflect the interests of others. Web portals have attempted to customize content for users, some web portals group content per language, other web portals allow customization of a news section so that whenever users visit the portal, the type of news stories users are registered for are shown to each user. Greater degrees of customization of content require more storage and processing power and hence encounter scalability issues. Web portals constantly intake vast quantities of content such as video, news stories, blogs, shopping sites. The content is processed to derive features that characterize it succinctly. Some examples include organizing the content in a hierarchy, describing content using methods from information retrieval. User behavior also varies widely, for example, some users visit a portal once every ten minutes, other users might visit once a day, or once a week, or even once a month. One challenge has been personalizing web content for each user based on the user's historic behavior.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.